Actor Gal Gadot speaks at an event to name Wonder Woman UN Honorary Ambassador for the Empowerment of Women and Girls at the United Nations Headquarters in New York, October 21, 2016.Reuters

Comic book character Wonder Woman was appointed The United Nations' new Honorary Ambassador for the Empowerment of Women and Girls on her 75th birthday on Friday. This will mark the launch of a campaign to promote gender equality and women's empowerment.

However, this appointment has sparked a lot of outrage, with more than 1,500 anonymous and "concerned" UN staff members saying it wasn't an appropriate choice. They have even signed an online petition, saying it was disappointing that the UN was unable to find a real woman to champion the causes of gender equality and women empowerment.

According to these anonymous staff members, it is important to have "strong (living, breathing)" female role models to attain the goal of empowerment of women and girls.

The online petition reads: "Although the original creators may have intended Wonder Woman to represent a strong and independent 'warrior' woman with a feminist message, the reality is that the character's current iteration is that of a large breasted, white woman of impossible proportions, scantily clad in a shimmery, thigh-baring body suit with an American flag motif and knee high boots – the epitome of a 'pin-up' girl."

To celebrate Wonder Woman's 75th birthday, director Zack Snyder released a new photo of Gal Gadot as Princess Diana of Thermyscira, from his upcoming Justice League movie. The movie will debut in theaters on November 17 2017.